1. Field of the Invention
The field of the invention is three dimensional television, their camera systems and their receiver or monitor systems.
2. Description of the Related Art
Certainly the most common example of three dimensional image perception is the example of a person's vision. When viewing an object, a person's eyes usually are situated at the same vertical height but separated horizontally by 2 1/2 inches or so. As each eye sees the same scene, the perspective each eye sees of the scene is slightly different. For example, the left eye, because of its spaced-apart position from the right eye, will see just slightly more or less around a corner or curved surface than the right eye. If the scene viewed by the eyes is broken up into many very small dots of viewing perception, the left retina will receive some dots which are horizontally displaced from dots received by the right eye due to depth difference and due to the fact that the left eye is spaced apart from the right eye. However, no "advantage" is gained vertically since there is no vertical displacement between the eyes and the same vertical component is seen by both eyes. The person's brain receives the images from each eye and, bu processes not yet understood, compares and combines the images to give a 3-dimensional sense to the scene viewed by the person.
It is thus clear that the lessons of the eye may be applied to television camera and receiver systems by utilizing two closely spaced television cameras viewing the same scene whereupon the video signal output of each camera is directed to a pair of television receivers. The scene viewed by each camera is repeated on the cathode ray tube of a respective receiver. Then, if a party were to view the two receivers steroscopically, i.e., where a person's left eye could only view the CRT of the television receiver receiving the output of the left television camera and the right eye viewing only the CRT of the television system receiving the output of the right television camera, the eyes would then see on the television CRTs exactly what they would see if they were viewing the scene themselves. The person's brain would interpret the two displays to reveal its 3-dimensional aspects. Map makers employ similar techniques when they view photographs taken from adjacent cameras (or from a single camera which is moving in a straight-line motion) through a stereoscope to determine height information of the ground or perhaps more commonly, to draw elevation contour lines on maps.
Now there has been much effort in the field of reproducing scenes on television receiver CRTs that take on the appearance of 3-dimension. For example, Drewlo, in U.S. Pat. No. 4,963,959, describes a 3- dimensional cathode ray tube display wherein two television cameras view the scene from different points. The output electronic video signals from the two cameras are mixed and then transmitted via a broadcast antenna. The resultant composite signal is received by a sole video receiver which separates the electronic signals of the two cameras. Then, in a time division multiplex, each signal is applied in time to the electron gun at the rear of the cathode ray tube. In an alternate embodiment, the cathode ray tube incorporates a pair of electron guns, one for each of the signals from the cameras. When one electron gun is utilized, and utilizing time multiplexing, one camera's output is shown on the TV screen and the displayed image directed via a prism surface to the viewer's left eye. Subsequently, the second camera display is routed through a separate prism to the viewer's right eye. Thus with the two gun approach, each gun is so oriented as to display the scene on separate portions of the cathode ray tube such that each portion is viewed by different eyes. Such is accomplished by constructing the cathode ray tube display surface as a linear Fresnel lens. Because the viewer is receiving independent video screens related to their eyes, the result is the perception of depth.
In other 3- dimensional display apparatus disclosed in United Kingdom Patent Application No. 2,206,763, a cathode ray tube is viewed through a lens, such as a lenticular array, followed by a spatial light modulator such as a liquid crystal display. Different views of the scene are provided on the cathode ray tube in a time-multiplex manner. By such apparatus, different views and directions from which they are visible correspond to different views of the scene and thus the appearance of 3-dimensions is given.
Still other devices, such as that shown in U.S. Pat. No. 4,943,860 to Hattori, utilize a Fresnel lens in front of a cathode ray tube display as the substantial part of 3-dimensional viewing. Utilizing Fresnel lens or lenticular lens between the cathode ray tube display and the viewer is a popular scheme in attempting to present 3-D viewing of a television CRT.
However, from the very fact that past attempts of 3-dimensional television have not been widely adopted, it is obvious that the systems heretofore proposed both by the inventors recited above and other systems which abound have not met with great public acceptance.
Accordingly, it is obvious that there is need for a 3-dimensional television camera and receiver system which overcomes problems inherent with the above systems, and in addition is easy to implement and relatively inexpensive.